1. Field of the Invention
The present invention relates to a declutching device for a clutch, in particular for a mechanical diaphragm clutch for a motor vehicle.
More particularly, the invention relates to a declutching device for a clutch, for acting on a clutch disengagement means, especially for a mechanical clutch for a motor vehicle, and comprising an external body for fastening the declutching device on a fixed part, an axially oriented annular blind cavity defined by a guide tube which is delimited radially outwardly by an outer tube, the guiding profile of which is followed by the external body, and further comprising a piston which penetrates into the blind cavity so as to define a variable volume control chamber, and of the type in which the outer tube includes an orifice for feeding fluid to the chamber, which is connected to a feed duct that is in communication, with a bore of the external body the orientation of which is generally radial and which is formed facing the feed orifice of the outer tube, through a tubular element sealingly attached to and mounted in the bore.
2. Description of Related Art
Such a declutching device, with hydraulic control obtained by means of the piston, is described and shown in French patent application No. 98 07970 filed on Jun. 19, 1998, and also in FIG. 1 attached to the present description.
In that document, in order to provide good sealing between the external body and the outer tube around the fluid feed orifice of the chamber, the tubular sealing element is interposed axially in the bore between the outer tube, with a sealing gasket being interposed, and the end of a connecting duct which is itself connected sealingly on the external body.
An object of the invention is to propose a declutching device of the type set forth above in which the various sealing means are more effective, and the design of which enables improved modularity of the components to be obtained, in particular with a view to having a range of hydraulically controlled declutching devices at reduced cost, so as, in particular, to facilitate the geometric disposition of the connecting duct with respect to the external body.
With this in view, the invention proposes a device characterised in that the radially outer end of the tubular element is blind, and in that the feed duct is connected to a through hole of the external body which is open transversely into the bore in line with a passage formed in the wall of the tubular sealing element.
This feature simplifies the management of the seals between the external body and the outer tube on the one hand, and between the feed duct and the external body on the other hand, and makes them independent while permitting the disposition and orientation of the feed duct and its connecting through hole, independently of the orientation and position of the bore and of the attached tubular sealing element.
In addition, the tubular sealing element is in the form of a sealing xe2x80x9ccartridgexe2x80x9d, the conditions for the manufacture and sealed fitting of which are improved.
In accordance with further features of the invention:
the tubular sealing element carries at least one annular seal which is in cooperation with the wall of the bore;
the annular seal is disposed between the said passage and the radially inner end of the tubular sealing element, thus ensuring complementary sealing between the chamber and the external body;
the tubular sealing element carries a second annular seal disposed between the said passage and the radially outer end of the tubular sealing element, completing the seal between the sealing cartridge and the bore in which it is sealingly mounted;
an annular sealing gasket is mounted in compression between the radially inner transverse annular end face of the tubular sealing element and a facing portion of the outer wall of the outer tube that surrounds the feed orifice, and which avoids leakages of liquid between the outer tube and the external body;
the annular sealing gasket is an element which is fitted between the radially inner transverse annular end face of the tubular sealing element and the facing portion of the outer wall of the outer tube, or, in another version, the annular sealing gasket is made by moulding in one piece with the tubular sealing element, in particular by a two-material injection moulding technique;
the passage is at least one hole formed in the wall of the tubular sealing element, in order to put the interior of the tubular sealing cartridge into communication with its periphery or outer wall;
the tubular sealing element has an internal radial groove into which the said hole is open, thereby permitting various orientations and positions of the connecting through hole, by using the same cartridge and arranging it so that the angular orientation of the cartridge in its bore does not matter;
the tubular sealing element is immobilised axially in the bore which receives it, by fastening means which are arranged at the radially outer end of the bore, so as to retain it axially within the bore by axially compressing the annular seal and, where appropriate, providing additional sealing in the region of the fastening means;
the fastening means comprise a radial abutment shoulder formed within the bore, which extends facing the radially outer annular transverse axial end face of the tubular sealing element;
the shoulder is formed integrally with the body, in particular by deformation of the latter after the tubular sealing element has been fitted in place;
the abutment shoulder is an annular ring attached within the bore;
the tubular sealing element is immobilised axially, in the bore which receives it, by sealed welding, in particular with external application of heat from its radially outer end portion into the corresponding portion of the bore;
the tubular sealing element is immobilised axially, in the bore which receives it, by sealed adhesive bonding of its radially outer end portion in the corresponding portion of the bore;
the tubular sealing element is immobilised axially, in the bore that receives it, by screw-fastening of its radially outer end portion in the corresponding portion of the bore;
the tubular sealing element is immobilised axially by force-fitting in the bore that receives it;
the tubular sealing element is immobilised axially, in the bore that receives it, by complementary fastening means with elastic mating engagement;
the tubular sealing element is immobilised axially, in the bore that receives it, by complementary fastening means defining a cotter pin;
the body is a plastics moulding;
the outer tube is a metal tube;
the tubular sealing element is a plastics moulding.